A toner cartridge provided on an image forming apparatus such as a laser printer for storing a developing agent is known in general.
For example, a double-structure toner box including a container body storing a toner and an outer casing receiving and pivotably supporting the container body is known as such a toner cartridge.
The container body is provided with a toner discharging port, and the outer casing is provided with an opening opposable to the toner discharging port. In this toner box, the toner can be discharged from the container body by pivoting the container body to oppose the discharging port and the opening to each other and open the discharging port. On the other hand, discharge of the toner from the discharging port can be regulated by pivoting the container body to shift the discharging port and the opening from each other and close the discharging port.
A seal member is provided on the outer peripheral surface of the container body, to surround the discharging port. This seal member is in contact with the inner peripheral surface of the outer casing to block the clearance between the container body and the outer casing, thereby preventing leakage of a developing agent from the discharging port.
In this toner box, the seal member is in contact with the inner peripheral surface of the outer casing. When the container body is pivoted for opening/closing the discharging port, therefore, the seal member may be caught by an edge of the opening provided on the outer casing and separated from the container body.
In this toner box, further, the seal member must be regularly in contact with the inner peripheral surface of the outer casing, in order to prevent leakage of the developing agent. If the container body is pivoted in this state, resistance is caused in the pivot of the container body due to friction between the seal member and the inner peripheral surface of the outer casing, and hence the operability related to opening/closing of the discharging port may be reduced.